Circuit connection for thermionic tubes



Sept. 11.,.1934. L. KRos v 4'CRCUI'I CONNECTION FOR THERMIONIC TUBESFiled may 2s. 192s jnv-renfor 141g 20 J3 lszL /lA/o'ro'ls Patented Sept.1l, 1934 UNITED STATES PATENT koFFIcI-z Lszl K'rs, Budapest, HungaryApplication Mey 2'3, 1929, serial No. 365,324

In Germany June 6, 1928 6 Claims.

tive potential to be used as grid bias.` A furtherobject of` theinvention is to produce different constant voltages for several anodecircuits supplied from a common feed line. A still further object of theinvention is to provide a new potential divider adapted in particularfor carry- ,ing out connections according to the inventionl andpermitting the taking off from a direct current potential of reducedpotentials of lany desired constant value.

According to the invention, a useful potential drop in an anode circuitis produced by connecting inthe anodecircuit aconductor which varies itsresistance according to the load at the moment in such manner that thepotential drop in it remains practically constant between certain limitsof the load.f

As such conductors, tubes filled with rarefled gas, for example, neon,with two or more eleotrodes, cold or heated, or partly cold and partlyheated, may be used.

To simplify expressions, such conductors will in the following bedescribed as balance conductors.

It is already known that a constant potential may be taken off theterminals of a discharge tube through which ows a variable current andwhich represents a balance conductor. Such a discharge tube has alsobeen connected in parallel to an anode Circuit in order to make thepoten--l tial of this anode circuit practically independent of thevariations of the load. Where, however, it was desired to produce a dropof potential in the anode circuit, that is, in series, with thethermionic tube, ohmic resistances have hitherto been used. Thisresulted in a drop of potential varying with the load.

By using, in accordance with the invention, a balance conductor for theproduction of the potential drop desired in the anode circuit, not onlyi is the independence of the potential drop on the load secured but atthe same time numerous other 55 new advantages are obtained which are'of great the above-mentioned distortions are avoided.

(Cl. 25o-27) importance for the correct working of the thermionic tubes.l

A considerable ohmic resistance in the anode circuit represents a highresistance for the modulations of the speaking currents and therebyreduces the sensitiveness or amplifying action of the thermionic tubes.To conduct the modula' tions, a condenser must therefore be connected inparallel to the ohmic resistance, which condenser, however, transmitsthe various frequeng5 cies in unequal measure and thereby causesdistortions in the modulations. In case several anode circuits areconnected in parallel, an ohmic` resistance connected in seriestherewith forms a coupling resistance between the various anode circuitswhereby the amplifier tubes are easily put in oscillation, which dangeris still further considerably increased if, as usual, grid biaspotentials are taken from the coupling resistance.

A balance conductor forms an extremely small resistance for themodulations of the speaking currents, the value of which is furthermoreindependent of the frequencies. Thanks to this high conductivity formodulation Currents," neither the above-mentioned prejudical effect onthe sensitiveness or the amplifying action of the thermionic tubes northe bad effects of the coupling are to be feared, and due to theindependence of the conductivity of the frequencies,

The connection according to the invention is of peculiar practicalimportance in the taking of a negative grid bias potential from theanode circuit and in the feeding ^of several anode circuits withdifferent potentials from a common feed line. Constant grid biaspotentials may be taken from a balance conductor connected behind thenlament or filaments. By the Iconnection of balance conductors in thebranches of a common feed line, all of the anodes lying in the severalbranches may be supplied with constant poten' tials of any desired valueif only the potential of the common feed line be made independent of thevariations of the load which is possible by bridging over the commonfeed line by means of a balance conductor, that is, bythe knownconnection, mentioned at the outset, of afbalance conductor parallel tothat anode circuit which is to be supplied with the undivided potentialof the common feed line.

The invention also comprises a new potential divider which is adapted inparticular for carrying outconnections, according to the invention, withtwo or more balance conductors. This potential divider ils composed ofglow discharge tubes lled 110 or terminals. The different tubes of suchla potential divider may have a common socket. It is also possible toenclose the electrodes of two or .more glow discharge tubes of apotential divider in a common container or gas space.

In the accompanying drawing- Fig. 1 diagrammatically shows a connection,according to the invention, in which they constant drop of potential ina balance conductor connected behind'the filament is utilized for takingoff constant grid potentials.

Figs. 2 and 3 show, also diagrammatically, two forms of construction ofanother connection, according to the invention, for the supply ofseveral anodes with different potentials from a. common feed line, wherethe balance conductors connected in series to the anodes lying in thebranches of the feed line eiect a distribution oi' the potentialindependent of the variations of the load.

Fig. 4 shows the combination of the connections according to Figs. 1 and3.

Figs. 5 and 6 are diagrammatic representations of potential dividers forthe connections according to Figs. 2 and 4, respectively.

Fig. 7 shows a further constructional form of the potential divideraccording to the invention, in diagram, and

Figs. 8 to 10 show in side, top and bottom view,

, a practical construction corresponding to the diagram according toFig. 7. In the bottom view is also shown the connection of the severalglow discharge tubes between each other and with the plug contacts,inndiagram.

In Figs. 5 to 7 and 10, the numberslinserted in the individual glowdischarge tubes indicate the constant potential drop taking place in,and being characteristic of, the corresponding tube, while the numberswhich in Figs. 5 to 7 are enclosed in brackets under the referencecharacters for the terminals and according to Fig. 10 are marked 'on thebase plate, give the Value of the constant potential which may be takenfrom the corresponding terminal.

Figs. 11 and 12 show modications of the connections according to Figs. 2and 4, respectively, in which the' several balance conductors areenclosed in a common container.

In the connection according to Fig. 1, any-desired current source with'comparatively high internal resistance, lies between 1 and 2, whichcurrent source is intended to supply anode and grid potentials forthermionicv tubes (not shown) which are connected with the anodes at 3,and with the iilaments at 4. In thelead between 4 and 2 is connected abalance conductor 5 having a comparatively high ohmic resistance 6connected as a potentiometer parallel thereto, the balance conductorhaving 4a negligible ohmic resistance. At the tappings 7 and 8 of thepotentiometer 6, grid bias potentials are taken oi for the thermionictubes supplied. The condensers 9 and 10 serve to conduct the charginganddischarging currents of the grids and of the transformer coils lyingthereon. By means `of the condenser 11 the resistance of the anodecircuit to alternating current is reduced.

As the potential drop in the balance conductor 5 mainly depends on theconstants thereof, remaining practically unaffected by the variations ofthe current strength i'n the anode circuits,

while from the tappings. of the ohmic poten-A the load in the anodesupply line.A As the potenv tiometer 6 only supplies potential and nocurrent is taken therefrom, its resistance may be selected as high asdesired.

Itwill be understood that the potentiometer 6 is only necessary for biaspotentials which do not reach the working potential of the balanceconductor 5. On` the other hand, bias potentials above the workingpotential of a balance conductor could be taken from several balanceconductors connected in series to each other which may be arranged in acommon container as in Fig. 12, if desired.

According to Fig. 2 the potential between the terminals 12 and 13 of aknown anode mains supply appliance, a so-called B eliminator,represented by coil 14 and condenser 15 is in known manner in so farmade independent of the variations of the load by the balance conductor16 connected in parallel that it cannot appreciably rise over theworking potential of the balance conductor 16. So long as the load doesnot exceed a definite upper limit, the potential between 3 and 4 maytherefore be considered as practically constant. By the connection inthe sense of the invention of further balance conductors, thispotential, available as constant highest potential, may now be reducedto lower anode potentials also constant. In branches of the common feedline between 12 and 3, balance conductors 19 and 20, respectively, areconnected in series to anodes to be connected at -17 and 18 whereby eachof the anodes connected at 17 and 18 receives a constant potential whichis smaller by the potential drop in the balance conductors 19 and 20,respectively, connected in series with the corresponding anode, than thepotential between 3 and 4. As ordinary glow discharge tubes having coldelectrodes may be made as balance conductors for the most varyingpotentials over 80 volts, this connection permits of the production andstabili-- zation of any desired potential value for anodes, also under80 volts, by means of .ordinary glow discharge tubes. The condensers 21and 22 reduce for higher frequencies the alternating current resistancein the corresponding anode circuits.

The connection according to Fig. 3 differs from that shown in Fig. 2 inthat the balance conductors 19','20' and 16' are arranged inpotentiometer connection. It needs, of course, no further explanationthat in this case the potential between 18' and 4 is less by the sum ofthe potential drops in 19' and 20' than between 3 and 4, and that thehighest value of the potential, between 3 and 4, corresponds to the sumof the working potentials of 19', 20 and 16. Of course, the number ofthe balance` conductors arranged in series to each other may be chosenas desired.

The combination shown in Fig. 4 of the connections according to Figs. 1and 3; needs no further description.

Fig. 5 shows a potential divider adapted for the connection according toFig. 2 and consisting of three glow discharge tubes 16. 19, 20 whichhave their anodes joined.- The connected anodes have a common terminalb1, whereas each of the three cathodes is provided with a separate"terminal b2, b3, b4. The glow tube 16 which in the connection accordingto Fig. 2 serves for the bridging over of the common feed line, musthave a working potential equal to the potential between 3 and 4, thatis, the potential between 3 and 4 must be adjusted to the workingpotential of the glow tube 16. A potential divider accordi g to theinvention permits of this regulation without the use of an instrument.It is sufficient to bring to a glow the glow tube 16 by means of arheostat connected on the current source. In order that this tube to beobserved may be easily distinguished from the other tubes of thepotential divider, and still more, in order that the observation may notbe interferedfwith by the light effect of the other tubes, which in somecases may glow before, the other tubes are provided with an opaquecoating, as is indicated on the drawing by shading.

For the purpose of the connection according to Fig. 2, the glow tubes 19and 20 of the potential divider are so selected that their workingpotentials complement the anode potentials desired at 1'7 and 18 up tothe workingpotential of the glow tube 16. With the working potentials ofthe glow tubes as indicated in Fig. 5, the total potential of 200 voltsbetween 3 and 4 is therefore reduced by the glow tubes 19 and 20, theworking potentials of which respectively amount to 100 and 180 volts, to100 and 20 volts respectively, which reduced potentials may be takenfrom the terminals b2 and b3 respectively. The stability of thepotentials taken off the potential divider according to the inventionpermits the terminals of the potenial divider to be marked once and forall with the values of the potentials to be taken therefrom.

Of course, a potential divider composed of glow tubes in the mannershown in Fig. 5 might comprise only two or also more than three tubes.

Fig. 6 shows a construction of the potential divider according to theinvention, which is adapted for the connections according to Figs. 3 and4. In this case, the several glow discharge tubes 19', 20', 16 and 5 areconnected in series est to each other. In the use for the connectionaccording to Fig. 3, the glow tube 5 remains out of working, the points2 and 4 being connected at the tapping b4 of the potential divider, andthe terminal b5 remaining free. In e use for the 'connection accordingtzr-Figgg4, point 4 is con- Also this regulation may be simply performedby bringing to a glow the tube 161 only.

It will be understood that also in cases where the tubes 19 and 20serving as potential reducers are connected in series to each other, thebridging over of the total potential may be effected by means of asingle tube connected in parallel to the series of potential reducingtubes.

In the potential divider according to Fig. 7,

the two forms of combination of the glow discharge tubes as shown inFigs. 5 and 6 are combined. The tubes a2, a1 and a4'are connected in-series as shown in Fig. 6, while the tube a3 joins this series by itsanode being connected to the anode of tube a2. With the use of glowtubes of the potentials indicated, the constant potentials may be` takenfrom the several terminals b as shown in brackets against the terminals.

In the construction -of the potential divider according to Figs. 8 to10, corresponding to the diagram of Fig. 7, the four glow tubes a1, a2,a3, a4 are mounted in a common socket d of insulating material shaped asa square base. The tubes are mounted in the top plate, and the terminalsb1, b2, b3, b4, b5 constructed in the manner of the known plug contacts,in the bottom of the base d. The vconnection of the tubes betweenvthemselves and with the terminals are made in the hollow space of thebase d according to the diagram seen in Fig. 10. With this constructionthe whole potential divider may be manipulated as a single tube.

Of course, a common socket for several tubes does not need to includeall the tubes of a potential divider.

The electrodes of two or more or all the glow tubes of a potentialdivider may also be enclosed in a common container or gas space. Fig. 11shows, for example, the connection according to Fig. 2 with a potentialdivider in which the several balance conductors 16,19 and 20 areconnected in the same manner as. in Fig. 2 but are enclosed in a commongas space, while in Fig. 12 a form of the connection according to Fig. 4is shown, in which the several balance conductors are replaced by asingle tube potential divider consisting of gaseous discharge pathsconnected and working in the same manner as the balance conductors 19',20', 16 and 5 of Fig. 4, except that one of the electrodes, to wit, themost negative cathode, is heated by means of a separate heaterlament 23supplied with heating current from any desired current sourcerepresented by the terminals 24 and 25. Those skilled in the art willreadily understand that any other method of heating may be applied -toheat this electrode or any number of the electrodes of the potentialdivider. The heat so applied results in the diminution of the cathodefall, that is, of the potential drop between the electrodes, .andpermits also a regulation of this potential drop by varying the measureof heating. Furthermore ,a discharge tube with heated electrodes may besmaller for a given load. Y

What I claim isz-'- 1. I`n a. system for energizing the grid electrodesof thermionic tubes from a current source of high internal resistance, adischarge device of predominatingly constant potential drop includingelectrodes in the negative conductor from the cathode to the currentsource, and means for applying said constant potential drop to the grid.v

2. The system as claimed in claim 1 in which grid biasing potentials areobtained from a potentiometer connected across twoelectrodes of 135stant the potential ofl the current supplied to the tube.

4. In a system for energizing the anode and 5. The system as claimed inclaim 4 in which grid biasing potentials are obtained from apotentiometer connected across two electrodes of said discharge device.

6. The system as claimed in claim 4 in which' anode potentials areobtained from the potential drop across two or more electrodes of saiddischarge device.

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